/* 修改后的CSS */
body {
    padding: 0;
    margin: 0;
}

header {
    text-align: center;
    max-width: 960px;
    min-width: 120px;
    margin: 0 auto;
}

nav {
    display: flex;
    justify-content: space-around;
    align-items: center;
}

.menu {
    position: relative;
    background-image: url('images/background-image-1.jpg');
}

.menu img.absolute {
    position: absolute;
}

main {
    display: flex;
}

article {
    flex: 3;
}

#sidebar1, #sidebar2 {
    flex: 1;
}

#sidebar1:hover, #sidebar2:hover {
    outline: 2px solid coral;
}

footer {
    margin: 0 auto;
    max-width: 960px;
    min-width: 120px;
    text-align: right;
}

.flex {
    display: flex;
    width: 80%;
    margin: 0 auto;
}

.fixed {
    font-size: 18px;
    font-weight: bold;
    color: coral;
    position: fixed;
    top: 0;
}

article img {
    float: left;
    margin-right: 20px;
}
